I. Field of the Invention
The present invention relates generally to electrical switch operation, particularly timed auxiliary wall switch operators and, more particularly, to a self-contained programmable wall switch operating system for use with an existing conventional wall switch having a toggle operator. The system accomplishes automatic time-variable switch positioning with a compact low cost pneumatic system which also requires very little power to operate.
II. Related Art
The related art includes a variety of devices designed to actuate standard wall mounted, toggle operated light switches. One such device, shown and described in U.S. Pat. No. 3,985,982, features battery operated embodiments designed to fit over a conventional switch wall plate (FIGS. 3, 5 and 6) and features a solenoid-operated push/pull rod with manual override and an electrical or wind-up timer control. Examples of other such devices can be found in U.S. Pat. Nos. 4,002,925, 4,645,942, 5,306,957, 5,397,869 and 5,719,362. While these devices will operate a standard wall switch automatically, semi-automatically or replace a standard wall switch with an automatically operating device, they are all rather complicated with many designs requiring gears, linkages, springs and other moving parts which generally need to be made to close tolerances which, in turn, results in high parts cost and extensive labor to assemble. This is generally not the only drawback as these devices also require more than a practical amount of power to operate. Therefore, because of shortened battery life, they do not lend themselves to practical self-contained battery-operated retrofit designs.
The need for a low-cost, low power retrofit device to operate a conventional wall switch automatically on a time-variable positioning basis is unquestioned. Present systems which, for example, turn lights on and off at various times of the day to simulate occupancy for vacationing home owners, or the like, are expensive devices which must be plugged in between the appliance and the power source. Since most new homes are built with wall switches to control a variety of lights, the desirability of a low cost means available to automatically control one or more switches to accommodate vacationing homeowners and to turn on lights for those returning from a day at work would be very desirable. Furthermore, a self-contained device which requires only the removal of the two screws holding the switch plate, the lifting off of the existing cover and the installation of the device in position and refastening of the screws enables any homeowner to install an automatic switch operator without any special skills. It would also be very desirable for such a device to accomplish a very large number of operations on a single set of integral batteries.
Accordingly, it is a primary object of the present invention to provide a device for automatically operating a conventional wall switch on a timed basis.
It is a further object of the present invention to provide a device for automatically operating a conventional wall switch that is small and self contained and uses a minimum number of moving parts.
A still further object of the present invention is to provide a device for automatically operating a conventional wall switch that is relatively inexpensive to buy and requires very little power to operate.
Another object of the present invention is to provide such a device that is compact and requires little additional space.
Yet another object of the present invention is to provide such as device which can be installed on an existing switch without electrical connection by one unskilled in the electrical arts.
These and other objects and advantages of the present invention will become clear to those skilled in the art upon familiarization with the further descriptions contained herein, together with the appended drawings.
By means of the present invention, problems and drawbacks associated with prior automated add-on electrical wall toggle switch operating devices are solved by the provision of a low-cost, reliable automated switch operator that also features low power consumption so that a single set of batteries can last for hundreds of cycles. It is the combination of low cost, reduced complexity and operating power requirement that make the switch operating system of the present invention more practical than previous devices of the class.
The system of the present invention is a self-contained unit that carries its own low voltage power supply and housing including a bottom plate that carries system components and is designed to mount in lieu of or over a conventional switch plate or box cover using the same or a similar pair of attaching screws. Installation is easily accomplished by even an unskilled homeowner as no electrical connections are involved.
The switch operating system of the present invention features pneumatic operation and includes a pneumatic operator which utilizes a solenoid-controlled miniature air pump and cylinder which, in turn, operates a ram. The ram is linked both to the wall switch toggle and a mechanical spring-biased catch and repel mechanism which may be a magnetic touch latch device such that when the air cylinder extends, the toggle is operated to one position, for example the xe2x80x9cONxe2x80x9d position and the latch spring is compressed in a latching mode. A solenoid is provided which closes and allows pressurization of the air cylinder when it is energized and vents the system when de-energized. The air cylinder and associated ram are caused to remain extended by the latch in its latching mode until the switch position is reversed even though air pressure is lost when the solenoid is de-energized. Upon a second pushing of the latch by the ram, the spring-loaded latch is put in a release or repel mode and the compressed latch spring is released which causes the ram to retract to its original starting position thereby reversing the position of the switch.
In this manner, electric power is necessary to xe2x80x9cflip the switchxe2x80x9d only in one direction and only a slight extension of the cylinder is required to activate the reversal of the latch. The unit further includes integral batteries, a programmable key pad and an LCD display so that the operation of the switch can be programmed in the manner of a night setback thermostat, or the like, the setting overridden or the device shut off, if desired.
It will be appreciated that the linear operating air cylinder and catch and repel mechanism or touch latch are the only moving parts in the system and they should operate reliably over thousands of cycles. Components of the system are all miniaturized and readily available commercially with the only modification necessary being the attachment of toggle-operating elements to the ram operated by the air cylinder.